Why can't I see the program that precedes a recording program?

Sorry if this is a newbie question, but I'm a 10 year user, just got a Roamio Plus.

Until now, if I was recording a program that started, let's say at 8pm on channel x, if I went to that channel at 8 and rewind and see the 7:30 program on channel x. Now, I can't do that; it won't rewind past the 8 pm recorded start.

What's up/ what am I doing wrong? Thanks.